In order to detect leaks in fluid systems, fluorescing dyes can be added to the fluid. The dyes become activated (i.e., fluoresce) when exposed to UV or high energy (short wavelength) blue visible light. Fluorescent additives enable targeted leak detection capable of determining the site of leakage of an operating fluid from a working system. Operating fluids such as lubricants, hydraulic fluids, heat transfer fluids, and refrigerants can all be treated with a dye additive which fluoresces when illuminated by suitable ultraviolet or visible blue light.
One such dye is the TP-3900 engine coolant dye sold by Spectronics Corporation, Westbury, N.Y., which fluoresces green when exposed to UV or high energy blue visible light. Blue water-based fluorescing dyes are also available for coolants or other fluid systems.
Fluorescence is generally understood to be a property that enables certain materials to absorb light energy and radiate visible light at a longer wavelength than the absorbed light. According to generally accepted theory, electrons in fluorescent materials are excited upon being illuminated by light energy of a specific wavelength, and light energy of a longer wavelength is radiated from these materials as the electrons return to the unexcited or ground state. The specific excitation and radiation wavelengths are characteristics of the particular fluorescent materials. The apparent brightness of a fluorescent material's luminescence is dependent on the wavelength emitted by the material and the intensity of the incident radiation that excites the material. For example, a fluorescent dye which has its excitation peak at a specific wavelength may quickly emit a much reduced luminescence as the wavelength of incident light deviates from the excitation peak, and will lose the ability to fluoresce when the incident light does not have enough energy within the specific excitation range.
The visibility of the fluorescent response is much increased when the intensity of other visible light is reduced, so that the fluorescent response is not masked or washed-out by other light. Thus, ultraviolet/blue leak detection lamps directed in otherwise dark conditions at an operating system containing a UV/blue responsive fluorescent dye will reveal leak sites which glow against the dark background.
Typical automotive fluids encompass a wide range of physical properties and include air conditioning refrigerant, engine lubricating oil, transmission fluid, brake fluid, power steering fluid, radiator coolant, diesel oil, and gasoline. In an auto repair facility, where diagnostic leak detection using fluorescent dyes is commonly performed on both air conditioning and other fluid systems, there is generally only one inspection lamp available for leak detection purposes. This light source may not be optimally, or even altogether, effective on the dye in the target fluid.
It would therefore be desirable to have a fluorescent dye for the various types of working fluids which is effective in all automotive working fluids, and which can be activated by the types of UV or high energy blue visible light lamps that are available in typical automotive repair facilities.